The current needs of railway technology impose having reliable systems for measuring the operating temperature of rolling bearings that equip railway axle-boxes.
As it is known, a railway axle-box is that component assembly that supports each end of a railway axle, which railway axle consists of an axle on which the wheels are shrunk on and which opposite ends are precisely carried in an idle manner by a pair of axle-boxes, which are restrained to the railway car by means of suitable suspensions. Each axle-box comprises an annular support, which accommodates the rolling bearing therein, and a closing cover. The rolling bearing receives one end of the axle on the inner ring and the cover closes the axle-box towards the outer sides of the railway car, thus covering and protecting the bearing and the end of the axle, which also normally carries a phonic wheel, which rotation speed is read by a specific sensor carried by the cover.
Since railway axle-boxes and the relevant covers may have the most disparate shapes, it is currently not possible to arrange a universal system, and therefore one which can be standardized, for reading the operating temperature of the axle-box bearing. It is also extremely difficult to retrofit existing railway axle-boxes with a temperature sensor for the same reason.